Welding head with toggle clamp

ABSTRACT

An in-place inert gas tube welder is disclosed which includes a head portion and a handle portion. The head portion includes a clamping means having an over center toggle for clamping the tubes to be welded. A sectored ring carries a nonconsumable tungsten electrode along a path adjacent the junction of of tubes to be welded. Inert gas is supplied to the welding chamber around the full 360* of the joint. A one-way clutch permits manual rotation of the sectored ring. The handle portion includes a drive motor for rotating the sectored ring, a means for supplying inert gas to the welding chamber, and a means for supplying electrical power to the electrode. An attachment means releasably secures the handle portion to the head portion. A supply cable is releasably connected to the handle portion for releasably connecting an inert gas source to the means for supplying inert gas to the welding chamber and for releasably connecting an electrical power source to the means for supplying electrical power to the electrode.

United States Patent Jeromson, Jr. et al.

[ Mar. 14, 1972 [54] WELDING HEAD WITH TOGGLE CLAMP The WeatherheadCompany, Cleveland, Ohio [22] Filed: Mar. 24, 1971 [211 Appl.No.:127,611

[73] Assignee:

3,534,199 10/1970 Downey et a].

Primary Examiner-C. L. Albritton Attorney-McNenny, Farrington, Pearneand Gordon [5 7] ABSTRACT An in-place inert gas tube welder is disclosedwhich includes a head portion and a handle portion. The head portionincludes a clamping means having an over center toggle for clamping thetubes to be welded. A sectored ring carries a nonconsumable tungstenelectrode along a path adjacent the junction of of tubes to be welded.inert gas is supplied to the welding chamber around the full 360 of thejoint. A one-way clutch permits manual rotation of the sectored ring.The handle portion includes a drive motor for rotating the sectoredring, a means for supplying inert gas to the welding chamber, and ameans for supplying electrical power to the electrode. An attachmentmeans releasably secures the handle portion to the head portion. Asupply cable is releasably connected to the handle portion forreleasably connecting an inert gas source to the means for supplyinginert gas to the welding chamber and for releasably connecting anelectrical power source to the means for supplying electrical power tothe electrode.

11 Claims, 9 Drawing Figures PATENTEDMARMISYZ 3,649,799

' SHEET1UF4 INVENTORS JAMES R JASIQOMJ'O/V, J Q,

PATENTEUHAR 14 m2 SHEET 3 OF 4 INVENTORS zwvas e Ja a/4.50M Joe, Ileoeaer M 4/E'A/A/4'A 4 y WELDING HEAD WITH TOGGLE CLAMP BACKGROUND OFTHE INVENTION This invention relates generally to welders, and moreparticularly to portable nonconsumable electrode inert gas welders forin-place welding of tubing and the like.

Portable inert gas welders of the type disclosed in US Pat. No.3,534,199 are widely used for in-place welding of tubing and the like.Such welders are particularly useful for in-place welding of tubing inaircraft assembly operations, since they require very little workingspace around the joint to be welded and further because the weld isperformed in an inert atmosphere.

Such prior art welders generally include a nonconsumable electrode whichis carried by a sectored carrier ring. The tubes that are to be weldedare positioned in the welder and clamped in place. Inert gas is suppliedto the welding chamber, and the carrier ring is rotated to move theelectrode about a path adjacent the junction of the tubes to be welded.After the welding, the clamps are opened to permit removal of the weldedjoint.

The clamping means for such prior art welders generally includes a fixedclamp and a movable clamp. The clamping means must usually operate tomove the movable clamp through a relatively large distance, because themovable clamp must move from a position adjacent the fixed clamp withinthe carrier ring to a position outside of the carrier ring a sufficientdistance to prevent removal of the workpiece. Furthermore, since thewelding operation may take several minutes the clamping means mustprovide a means to hold and lock the movable clamp in the closedposition.

To meet these requirements, clamping means for such prior art weldershave generally included a threaded rod extending from the movable clamp.A suitable screw thread means is provided to displace the threaded rodto move the movable clamp toward and away from the fixed clamp. Suchprior art clamping means are time consuming to operate, since the screwthread means must be rotated to displace the movable clamp from itsfully opened to its fully closed position. Furthermore, such prior artclamping means do not provide a means to insure that the correctclamping force will always be applied, particularly in view of thethermal expansion of the parts because of the heat produced during thewelding operation.

SUMMARY OF THE INVENTION These and other problems and disadvantages ofprior art inert gas welders are overcome by the present invention, whichprovides a welder having a clamping means which includes a handle meansand a link means for transmitting a force applied to the handle to amovable clamp and for multiplying the force applied to the handle solelywhen the movable clamp is in its closed position. In this manner, themovement of the handle means is minimized because the applied force isnot multiplied until the movable clamp is in the closed position. Afterthe movable clamp is in the closed position, however, the link meansincreases the applied force to insure an adequate clamping force. Theinvention further provides a lost motion and spring means for applyingthe increased force to the movable clamp. This insures that apredetermined clamping force will be applied regardless of minorvariations in the size of the workpiece and it will compensate for thethermal expansion of the parts being welded.

In a preferred embodiment, the inert gas welder includes a body portion,an electrode, a carrying means for carrying the electrode along a path,and a clamping means for clamping a tubular workpiece adjacent the path.The clamping means includes a first clamping portion and a firstattachment means securing the first clamping portion to the bodyportion. The clamping means further includes a second clamping portionand a second attachment means for securing the second clamping portionto the body portion and for moving the second clamping portion betweenan opened position away from the first clamping portion and a closedposition adjacent the first clamping portion. The second attachmentmeans includes a handle means and a link means. The handle means ismovable along a first path for moving the second clamping portionbetween the open position and the closed position and is further movablealong a second path to apply a clamping force to the second clampingportion. A link means transmits a force applied to the handle to thesecond clamping portion and through a toggle action multiplies the forceapplied to the handle when the second clamping portion is in the closedposition to minimize the required movement of the handle and by reachingan overcenter position holds the parts in a locked position. The linkmeans includes a spring means for applying the increased force to thesecond clamping portion so that the clamping force is applied regardlessof minor variations in the size of the workpiece. Because the first pathis substantially at right angles to the second path this minimizes thework space required to operate the welder.

BRIEF DESCRIPTION OF THE DRAWINGS These and other aspects and advantagesof the present invention will become readily apparent upon a fullunderstanding of the preferred embodiment shown in the drawings,wherein:

FIG. 1 is a perspective view of an inert gas welder according to thepresent invention with a workpiece clamped therein;

FIG. 2 is a bottom view of the welding head shown in FIG. 1 with thehandle portion removed and with the clamp shown in the open position;

FIG. 3 is a side elevational view of the welding head with one of itshousing side portions removed for clarity and with the clamp shown inthe closed position;

FIG. 4 is a side elevational view of the welding head with portionsbroken away to show the clamp linkage mechanism with the clamp in theopen position;

FIG. 5 is an enlarged exploded perspective view of the movable clampshowing one segment of the inert gas supply means;

FIG. 6 is an enlarged exploded perspective view of the stationary clampshowing the other segment of the inert gas supply means;

FIG. 7 is an enlarged exploded perspective view of the electrode carrierand the carrier retainer;

FIG. 8 is an enlarged schematic perspective view of the handle portionwith portions removed for clarity; and

FIG. 9 is an enlarged side elevational view of the attachment means forsecuring the handle portion to the body portion.

DESCRIPTION OF THE PREFERRED'EMBODIMENT Referring now to the drawings ingreater detail, FIG. 1 shows an inert gas welder having a welding headportion 10, a handle portion 11, and a supply cable 12. The welding headportion 10 includes a housing or body portion having two sections 13 and14, which are secured together in alignment by suitable screws 15. Eachsection is machined to provide suitable channels and surfaces forreceiving and positioning other parts of the welder and for definingportions of the welding chamber as described in detail hereinafter. Thesections 13 and 14 are provided with drilled gas passages 16 and 17,respectively, for conveying inert gas supplied by the handle portion 11to the welding chamber as explained in detail hereinafter.

FIGS. 1, 8 and 9 show the handle portion 11. The handle portion 11includes a main support member 20 and mating housing portions 21 and 22.The housing portions 21 and 22 are secured to the support member 20 andto one another by suitable screws 19, and provide a grip for theoperator. A start switch 23 and a stop switch 24 are provided to startand stop the welding cycle in the remote electrical welding controlwhich controls the operation of the control input to the welder. A gaspassage is provided to supply inert gas to the passages 16 and 17 of thewelding head portion 10 when the head portion and the handle portion 11are connected. This gas passage includes a gas tube 25 which extendsfrom the bottom of the handle portion 11 to the main support member 20.The gas passage further includes a passage 26 drilled in the mainsupport member 20 from the junction of the main support member 20 andthe tube 25. A transverse passage 27 is drilled laterally from side toside through the support member 20. When the head portion and the handleportion 11 are connected, the transverse passage 27 is aligned with thegas passages 16 and 17 of the head portion 10 to supply inert gasthereto.

A power unit 32 is also mounted on support member 20. The power unit 32includes a variable speed electric motor, a tachometer feedback unit forindicating the speed of the motor, and a gear reduction unit forincreasing the torque and decreasing the speed of the electric motoroutput. A pinion gear 33 is secured to the output shaft of the gearreduction unit of unit 32 by a shear pin (not shown) to provide drivingtorque for the welder electrode as explained in detail hereinafter. Anindicator light 28 is provided to indicate that the power supply unit 32is actuated and that a welding cycle is in progress.

A multiple pin male connector socket 34 is provided on the bottom end ofthe handle portion 11. The lead wires from the socket 34 are encasedwithin a sheath 35, and have been partially deleted from FIG. 8 forclarity. Two of the pins of connector socket 34 are utilized forsupplying electrical power to the electric motor of unit 32, and otherpins are used for the tachometer feedback of unit 32, start switch 23,stop switch 24, and indicator light 28. Still other pins areelectrically connected to an automatic positioning limit switch as willbe described in detail hereinafter. Bus bars 36 and 37 are provided tosupply electrical power to the electrode and to ground the welder.

The supply cable 12 is provided to releasably connect the controlequipment to the welder so that the control equipment can be used withmore than one welder. The supply cable 12 is provided with a plug whichis received by the lower portion of the handle portion 11, as may beunderstood with reference to FIG. 8. The supply cable 12 includes a gaspassage for supplying inert gas from a gas source to the gas supply tube25 and an electrical connector for connecting an electrical power sourceto the bus bars 36 and 37 for supplying electrical power to theelectrode. The supply cable 12 further includes an electrical connectorfor connecting each pin of connector socket 34 to the control equipment.

An attachment device is provided to releasably secure the head portion10 and the handle portion 11 together. In this manner, welding heads ofvarious sizes for accommodating tubing of various size ranges may beprovided without having to provide a complete welder for each such sizerange. Furthermore, this permits the tubing that is to be welded to beclamped in the head portion 10 without requiring the control equipmentand handle portion to remain idle.

As best seen in FIGS. 3, 8 and 9, the attachment device includesalignment surfaces for properly aligning the welding head portion 10 andthe handle portion 11, and a latch. The alignment surfaces include afirst alignment surface 40 and a second alignment surface 41 on thesupport member of handle portion 11. Third and fourth alignment surfaces42 and 43 are provided on the head portion 10 for engaging surfaces 40and 41, respectively, to align the head and handle portions of thewelder. The alignment surfaces 40 and 41 of the handle portion and thealignment surfaces 42 and 43 of the head portion are angularly relatedto one another to provide positive positioning of the head portion andhandle portion.

The latch includes a generally flat latching plate 45 secured to thehousing sections 13 and 14 of the welding head 10 by screws 46. A springlatch 47 is secured to handle portion 11 by screw 48. A latch shaft 49extends laterally through a suitable passage formed in the supportmember 20 of handle portion 11. The shaft 49 is provided with aflattened portion 50 adjacent the spring latch 47. A latch handle 51 issuitably secured to the shaft 49 so that rotational movement of thehandle 51 rotates shaft 49 to move spring latch 47 between its outwardposition of engagement with latching plate 45 and a retracted positionin which it is disengaged from plate 45 to permit separation of thehandle portion 11 from the head portion 10. The latching plate 45 andthe spring latch 47 are permanently affixed to the head portion 10 andhandle portion 1 1, respectively, so that there are no loose parts to behandled when the head and handle portions are separated.

The workpiece clamp for securing workpieces in the welder may be bestunderstood with reference to FIGS. 1-6. The clamp includes a stationaryclamping ,portion, a first attachment device for releasably attachingthe stationary clamping portion to the body portion, a movable clampingportion, and a second attachment device for securing the movableclamping portion to the body portion and for moving the movable clampingportion between an open position and a closed position.

The stationary clamping portion includes a left clamping member 57 and aright clamping member 58. The structural details of the clamping members57 and 58 are similar, and the left clamping member is shown in detailin FIG. 6. The left clamping member 57 includes a stationary clampingsurface 59 for engaging a tube 60 as shown in FIG. 1. The clampingmembers 57 and 58 are each provided with a suitable notch 56 for guidingthe second attachment device as explained below. The left and rightclamping members are received by suitable openings in the lateral sideportions 61 and 62 of housing sections 13 and 14, respectively. Thefirst attachment device includes screws 63 which extend through a flangeportion of each clamping member 57 and 58, and which are threadablyreceived by suitable threaded holes in the housing sections 13 and 14.In this manner, the stationary clamping members 57 and 58 may be easilyremoved so that replacement clamping members having clamping surfacesfor accommodating a different size tubing may be inserted. Because ofthe relatively large mass of the clamping members 57 and 58, and sinceclamping members 57 and 58 contact housing sections 13 and 14,respectively, over a relatively large surface area, heat flows from theworkpiece or tubes 60 and 60 to the clamping members 57 and 58 forcooling the tubes while they are being welded.

The movable clamping portion includes a left clamping member 64 and aright clamping member 65. Clamping members 64 and 65 are provided withclamping surfaces 66 and 67, respectively. In the preferred embodiment,each clamping surface is a stepped surface so that the portion havingthe smaller radius of curvature engages the respective one of tubes 60and 60 while the portion having the larger radius of curvature engages asleeve (not shown) which is positioned over the joint that is to bewelded.

The second attachment means includes a handle and a connecting linkage.The handle includes a hand receiving portion 73 and a link portion 74.The handle is movable along a straight line path between the positionshown in FIG. 4 and the position shown in phantom in FIG. 3 to move themovable clamping portion between an opened position away from thestationary clamping portion and a closed position adjacent thestationary clamping portion. The handle is further movable along asecond path between the position shown in phantom in FIG. 3 in which theworkpiece clamp is closed and the position shown by solid lines in FIG.3 to apply a clamping force. The second path is an arcuate path, as willbe explained in detail hereinafter, and is angularly related to thefirst path at an angle of substantially 90 to minimize the working spacerequired to move the handle to secure a workpiece in the welder.

The connecting linkage includes a movable clamp carrier member 75 towhich the movable clamping members 64 and 65 are secured by suitablescrews 76. A nylon insulator member 77 is cemented to the carrier 75 tominimize heat transfer through carrier 75 from the welding chamber. Aleft link rod 78 and a right link rod 79 are attached to carrier 75 bysuitable screws which are received by threaded holes 80 of carrier 75.The link rods 78 and 79 are received and guided by the notches 56in thestationary clamping members 57 and 58, respectively.

The link rods 78 and 79 are each secured to the handle by a similarlinkage. The linkage securing the right link rod 79 to the handle isbest seen in FIGS. 3 and 4. The left end of link rod 79 is slidablyreceived within a bore 86 ofa drag link 87. A generally flat washermember 88 is secured on the left end of link rod 79, such as by staking,and a coil spring 89 acts between the washer 88 and the drag link 87.The drag link 87 is a generally flat member, and a generally flat togglelink 90 is disposed between the drag link 87 and link portion 74 of thehandle. A first connecting pin 91 pivotally connects toggle link 90 todrag link 87, and pivotally connects a similar drag link (not shown) toa similar toggle link 93 (FIG. 1) of the linkage connecting left linkrod 78 to the handle means. A second connecting pin 92 pivotallyconnects the toggle link 90 to the link portion 74, and pivotallyconnects the toggle link 93 to the link portion 74. The drag link andtoggle link 93 for the left link rod 78, which are not shown in FIGS. 3and 4 but which are substantially similar to drag link 87 and togglelink 90, as well as about one-half of link portion 74, are slidablydisposed in a cutout passage 98 of the left housing section. 13. In asimilar manner, the drag link 87 and toggle link 90 are slidablydisposed in a cutout passage (not shown) of the right housing section14. A pivot pin 94 extends laterally between housing sections 13 and 14.A hook portion 95 is provided on link portion 74 for engaging pivot pin94 when the movable clamping portion is in its closed position.

When the workpieces have been positioned within the opened clamp asshown in FIG. 2, the handle is moved along the first path from theposition shown in FIG. 2 to the position shown in phantom in FIG. 3.This brings the clamping surfaces of the movable clamping portion to aclosed position adjacent the clamping surfaces of the stationaryclamping portion to encapsulate the workpieces on each side of the jointthat is to be welded. With the handle in this position, the hook portion95 engages pivot pin 94. The handle is then moved from the positionshown in phantom in FIG. 3 along a second path to the position shown bysolid lines in FIG. 3. When this occurs, the handle and hook portion 95pivot about the pivot pin 94 and the force applied to the handle istransmitted to toggle link 90 by connecting pin 92 and to drag link 87by connecting link 91. Because the right link rod 79 is slidablydisposed in bore 86, the force is then transmitted through spring 89 towasher 88 and link rod 79. In this manner, the coil spring 89 appliesthe clamping force to the workpiece so that a substantially constantclamping force is applied regardless of minor variations in diameter ofthe workpiece.

As the movable clamp is moved from its opened position to its closedposition and the handle is moved along the first path, the manual forceapplied to the handle is transmitted directly to the movable clamp.However, this force applied to the handle is multiplied to apply asubstantially greater clamping force when the movable clamp is in itsclosed position because of the toggle action produced when the handle ismoved along the second path. As a result, the greater movement of thehandle required by the mechanical advantage yielded by the connectinglinkage occurs only when the movable clamping portion is in its closedposition to minimize the working space required to actuate the handle.Also, the linkage is arranged such that the distance between the pivotpin 94 and the hand receiving portion 73 is greater than the distancebetween the pivot pin 94 and the connecting pin 92 to produce amechanical advantage greater than that produced by the toggle action oflink portion 74 and toggle link 90.

When the handle is in the closed position shown in FIG. 3, theconnecting linkage also locks the movable clamps 64 and 65 in the closedposition. To accomplish this, the connecting pin 92 is arranged suchthat it moves from a position vertically above the center of the pivotpin 94 to an overcenter position vertically below the center of pivotpin 94 when the handle is moved along its second path. Since the forceapplied to the connecting pin 92 by the toggle links and 93 is exertedin a horizontal direction as viewed in FIG. 3, the clamping force canpull the handle to the right only when the connecting pin 92 isvertically above the pivot pin 94. Because of this, the travel of theconnecting pin 92 over the center of the pivot pin 94 locks the movableclamps 64 and 65 in the closed position.

A bushing 96, which provides a bearing for a drive shaft as will beexplained in detail hereinafter, projects slightly into the cutoutpassage 98 as seen in FIGS. 3 and 4. When the movable clamping portionis in its opened position as shown in FIGS. 2 and 4, an end portion 97of drag link 87 compresses and passes over the projecting portion ofbushing 96. In this manner, a detent is provided to hold the movableclamping portion in its opened position without interferring with theoperation of the handle or linkage during any other portion of theiroperation.

The preferred embodiment further includes an electrode carrier 101, thestructural details of which are best seen in FIGS. 2, 3 and 7. Theelectrode carrier 10] includes two sections 102 and 103 formed of astrong, high temperature resistant insulating material such as boronnitride or other refractory material. An electrode shoe 104 ofconducting material such as beryllium copper is disposed about theoutside periphery of the carrier sections 102 and 103. A nonconsumableelectrode 105 of tungsten or the like is electrically connected to theshoe 104 and projects radially inwardly through the ceramic sections 102and 103. A carrier gear 106 is disposed on the side of carrier section102, and a spacer member 107 is disposed on the side of carrier section103. Connector pins 108, preferably-of filled nylon or teflon, extendlaterally through carrier sections 102 and 103, carrier gear 106 andspacer 107 and are held in place by suitable cement or adhesive toretain the various component parts of the electrode carrier in theirproper positions. An adjustment screw 109 is threadably received by alateral hole in the elec trode shoe 104. The screw 109 secures theelectrode in place and may be loosened to permit removal or adjustmentof the electrode 105. An actuating pin 110 projects from the exposedlateral side portion of section 103 to actuate a sensing device when theelectrode is in a predetermined position, as will be explained in detailhereinafter.

The electrode carrier 101 is rotatably journaled within a carrierretainer 116. The carrier retainer 116 is of nylon in the preferredembodiment, and includes an opening 117 for receiving the carrier 101. Aflexible brush 118 is provided to supply electrical power to theelectrode shoe 104 and electrode 105. Locating pins 119 project intosuitable holes (not shown) of housing section 13 to properly locate andposition the carrier retainer 116. A limitswitch 120 is disposed onretainer 116 and is provided with a resilient actuating arm 121. Theactuating arm 12] is arranged in interferring relation with actuatingpin 110, so that the limit switch 120 is actuated by pin 110 when theelectrode carrier 101 is in the position shown in the drawings. A firstswitch bus bar 122 is arranged on the carrier retainer 116 to engage asuitable electrical connector (not shown) on main support member 20 whenthe head and handle portions are joined together. The first electricalconnector is electrically connected to one of the pins of socket 34. Asecond bus bar 123 (see FIG. 2) is arranged on carrier retainer 116 toengage a second electrical contact (not shown) on support member 20. Thesecond electrical contact is electrically connected to another of thepins of socket 34. A third bus bar 124 is arranged on the carrierretainer 116 to engage a third electrical contact (not shown) on supportmember 20. The third electrical contact is also connected to one of thepins of socket 34. The first bus bar 122 and second bus bar 123 areelectrically connected to the two terminals of limit switch 120. Thethird bus bar 124 is electrically connected to the brush 118 to supplyelectrical power to electrode 105.

As may be best seen in FIG. 2, the stationary clamping members 57 and 58and the movable clamping members 64 and 65 extend through the annularcarrier gear 106 and the annular spacer member 107, respectively. Inthis manner, the cylindrical exterior surface of the stationary clampingmembers 57 and 58 cooperates with the cylindrical exterior surfaces 111and 112, respectively, of the movable clamping members to provide acontinuous cylindrical journal for the electrode carrier 101 as itrotates.

The drive train for driving the electrode carrier 101 is best seen I'nF-IGS. 2, 3, 7 and 8. As explained above, pinion 33 is connected to thedrive shaft of motor unit 32 by a shear pin. handle portion 11 isconnected to the welding head 10, pinion 33 engages a bevel gear 130which is rotatably mounted on a drive shaft 132. A helical clutch spring131 is secured to bevel gear 130 and is coiled about the drive shaft132. One end of the drive shaft 132 is rotatably journaled in bushing 96of housing section 13, and the other end of the drive shaft 132 isrotatably journaled in a similar bearing (not shown) in housing section14. A spur gear 133 is suitably connected to drive shaft 132 forrotational movement therewith. The free end of clutch spring 131 isadjacent spur gear 133 but is not connected thereto. ldler gears 134 and135 are rotatably journaled on shafts I36 and 137, respectively, whichare disposed on the carrier retainer 116. Each idler gear 134 and 135engages both spur gear 133 and carrier gear 106 to transmit drivingtorque therebetween and to preclude interruption of torque transmissionfrom gear 133 to carrier gear 106 when the opened portion of thesectored carrier gear 106 is adjacent one of the idler gears 134 or 135.One end of the drive shaft 132 projects through right housing section14, and a knurled knob 138 is suitably secured thereto.

When motor unit 32 is supplied with electrical power, it providesdriving torque for pinion 33 and bevel gear 130. As bevel gear 130 isrotated, it begins to rotate spring 131 in a direction to wrap thespring 131 more tightly on shaft 132 to rotate the shaft 132 therewith.This transmits the drive torque to the spur gear 133. Idler gears 134and 135 transmit the drive torque from spur gear 133 to carrier gear 106to rotate electrode carrier This moves the electrode 105 along acircular path adjacent the junction of the workpieces that are to bewelded.

If for any reason the electrode carrier is stopped in a position otherthan the open position shown in the drawings wherein the movable clampmay be opened to permit insertion of a workpiece, it may be desired tomanually rotate the carrier 101 back to its opened position. However,the gear reduction unit of the power unit 32 precludes manual rotationofthe drive motor through pinion 33. As best seen in FIG. 2, when theknurled knob 138 is rotated in a direction such that any frictionbetween shaft 132 and coil spring 131 tends to unwind the spring, thespring 131 effectively disconnects the bevel gear 130 and motor unit 32from shaft 132 to permit rotating torque to be applied to carrier gear106 through spur gear 133. This provides a clutch to permit such manualrotation of the electrode carrier 101 without requiring a neutralposition in the drive train gear unit.

As explained above, the supply cable 12 includes a gas passage tointerconnect an inert gas source with tube 25 of the handle portion 11.The gas is then conveyed through tube 25 to passages 26 and 27 ofsupport member 20. From passage 27, the inert gas is then conveyed topassages 16 and 17 in housing sections 13 and 14, respectively. Thestructure for conveying the inert gas from passages 16 and 17 to thewelding chamber is best seen in FIGS. 2, 5 and 6. The left stationaryclamping member 57 is provided with a passage 142 which extends radiallyinwardly from its outer periphery to intersect a transverse passage 143.The transverse passage 143 extends to an annular groove 144 in theradial side wall 145 of the clamping member 57. An annular distributingmember segment 146 having a notched external periphery 147 is receivedby annular groove segment 144 so that its radial side wall 148 isaligned with radial side wall 145. The thickness of distributing membersegment 146 is less than the depth of groove 144 so that a segment of anannular manifold is defined between the bottom portion of groove 144 anda sidewall portion of distributing member 146. In a similar manner, anannular groove segment 149 is provided in left movable clamping member64 for receiving an annular distributing member segment 150. The segment150 includes a notched external periphery 151. The thickness of thedistributing member segment 150 is less than the depth of annular groove149, so that a segment of an annular manifold is defined between thedistributor segment 150 and the bottom of the annular groove 149 whenthe radial sidewall 152 of segment 150 is aligned with the radialsidewall 153 of left clamping member 64.

When the movable clamping portion is in the closed position, the abovedescribed manifold segment of stationary clamping member 57 will bealigned with the above described manifold segment of clamping member 64.This permits the inert gas to be supplied to the welding chamber throughthe notched portions of the distributor segments 146 and 150. An

identical inert gas supply structure is provided in right clampingmembers 58 and 65. By introducing the inert gas into the welding chamberthrough sidewall portions of the workpiece clamp, the inert gas isintroduced immediately adjacent the path of the electrode to remove hotgases and contaminates from the inlet location adjacent the electrodepath. Furthermore, this provides a structure for introducing the inertgas along the entire electrode path at both sides of the electrode toinsure a uniform welding atmosphere and a uniform gas cooling of theweld.

As best seen in FIGS. 2 and 5, an indicator tab 157 is slidably receivedbetween the right clamping member 65 and the clamp carrier member 75. Acoil spring 158 biases the indicator tab 157 to its outward positionshown in the drawings. The portion of the indicator tab 157 which isreceived between the clamping member 65 and the clamp carrier member 75extends to the inner surface 159 of the clamp carrier 75. When themovable clamping portion is closed and it is desired to determine if theelectrode carrier 101 is in the opened position shown in the drawings,the indicator tab 157 is manually pressed inwardly. If the electrodecarrier is in the position shown in the drawings, the portion of theindicator tab 157 adjacent the inner surface 159 will project into theremoved portion of the sectored carrier 101 to permit the indicator tab157 to be pressed inwardly. However, if the carrier 10] is not in thisposition, the portion of the indicator tab adjacent the inner surface159 will contact the carrier 10] and preclude such inward movement ofthe tab 157.

To operate the inert gas welder shown in the drawings, the welding head10 may be separated from the handle portion 11 at the completion of aprior weld so that the handle portion 11 may be used with anotherwelding head while a workpiece is being clamped in the welding head 10.With the welding head so separated, tubes 60 and 60 are inserted in theopened clamping means shown in FIGS. 2 and 4. If desired, a sleeve maybe placed about the joint that is to be welded in a wellknown manner.The handle is moved along its first path from the position shown inFIGS. 2 and 4 to the position shown in phantom in FIG. 3 to close themovable clamps 64 and 65. The handle is then moved along its second pathfrom the position shown in phantom in FIG. 3 to the position shown bysolid lines in FIG. 3. This applies a predetermined clamping force tothe workpieces and locks the movable clamps 64 and 65 in the closedposition. An inert gas supply is connected to the free end of the tube60, and a restricted orifice is connected to the free end of tube 60 toprovide an inert atmosphere inside of the tube.

The handle portion 11 and supply cable 12 are then connected to thewelding head 10 to connect the control equipment (not shown) to thewelding head 10. The control equipment, in a well-known manner, includesan inert gas supply, an electrode power supply, and a motor powersupply. Prior to the commencement of a welding cycle, the inert gassupply control purges the welding chamber with an inert gas such asargon and then supplies a steady flow of inert gas to the weldingchamber throughout the weld. The gas escapes through various clearancesof the welding head, such as the clearances between the clamp carrier 75and the housing sections 13 and 14.

Once the welding chamber has been purged, the electrode power supply isactuated to establish an arc. ln a typical welding cycle, the motorpower supply then provides a substantially constant direct currentvoltage to the motor to run the motor at a substantially constant speedand rotate the electrode carrier 101 at a substantially constant speed.With the electrode rotating at a substantially constant speed, and afteran arc has been established, the electrode power supply begins toincrease the electrode current until a desired steady state current hasbeen obtained. The s'teady state motor speed and electrode current thencontinue for a predetermined time, such as the time required. for onecomplete rotation of the electrode carrier 10]. Toward the end of thewelding cycle, the speed of the motor is increased while the electrodecurrent remains the same. Finally, the motorspeed is increased stillmore while the electrode current is decreased to zero during a run-outportion of the cycle to produce an even weld. The welding cycle mayextend over any desired timeperiod, such as that required for two orthree revolutions of the electrode carrier. Although a typical weldingcycle has been described, various relationships between the electrodecurrent and the electrode carrier speed and the rate of change of eachmay be used, depending upon the particular workpiece that is to bewelded and the type of inert gas that is used. When the end of thewelding cycle is reached and the electrode carrier 101 returns to itsopen position, the actuating pin 110 actuates limit switch 120 to stopthe electrode carrier. The handle portion 11 may then be removed fromthe welding head 10 so that the handle portion 11, the supply cable 12and the control equipment may again be used to operate another weldinghead. The workpiece clamp is then opened, and the workpiece removedtherefrom.

Although a specific embodiment of the invention has been shown anddescribed in detail, various modifications and rearrangements may bemade without departing from the scope of the invention defined by thefollowing claims.

We claim:

1. An inert gas welder comprising a body portion, a welding chamber, anelectrode, a carrier means for carrying said electrode along a path, anda clamping means for clamping a tubular workpiece to be welded adjacentsaid path; said clamping means including a first clamping portion havinga first contoured clamping surface, first attachment means for securingsaid first clamping portion to said body portion, a second clampingportion having a second contoured clamping surface for cooperating withsaid first clamping surface to clamp said workpiece adjacent said path,and a second attachment means for securing said second clamping portionto said body portion and for moving said second clamping portion betweenan open position away from said first clamping portion and a closedposition adjacent said first clamping portion; and said secondattachment means including handle means movable along a handle path, andspring means interconnecting said handle means and said second clampingportion for permitting movement of said handle means along said handlepath when said second clamping portion is in said closed position.

2. An inert gas welder as set forth in claim 1 wherein said spring meansprovides the sole means for transmitting force between said handle meansand said second clamping portion.

3. An inert gas welder as set forth in claim 2 wherein said secondattachment means includes overcenter locking means for locking saidhandle means in a predetermined position along said handle path.

4. An inert gas welder comprising a body portion, a welding chamber, anelectrode, a carrier means for carrying said electrode along a path, anda clamping means for clamping a tubular workpiece to be welded adjacentsaid path; said clamping means including a first clamping portion havinga first contoured clamping surface, first attachment means for securingsaid first clamping portion to said body ortion, a second clampingportion having a second contoure clamping surface for cooperating withsaid first clamping surface to clamp said workpiece adjacent said path,and a second attachment means for securing said second clamping portionto said body portion and for moving said second clamping portion betweenan open position away from said first clamping portion and a closedposition adjacent said first clamping portion; said second at tachmentmeans including handle means movable along a first path between a firstposition and a second position for moving said second clamping portionbetween said open position and said closed position, said handle meansbeing further movable along a second path between said second positionand a third position, link means for transmitting a force applied tosaid handle means to said second clamping portion and for multiplyingsaid force applied to said handle means solely when said second clampingportion is in said closed position and said handle means is moved fromsaid second position to said third position, and said link meansincluding spring means for applying said increased force to said secondclamping portion when said second clamping portion is in said closedposition.

5. An inert gas welder as set forth in claim 4 wherein said body portionincludes means for defining said first path of movement of said handlemeans, and said link means includes means for defining said second pathof movement of said handle means.

6. An inert gas welder as set forth in claim 4 wherein said first pathis a substantially straight line, and said second path is angularlyrelated to said first path.

7. An inert gas welder as set forth in claim 6 wherein said angularrelationship is substantially a right angle.

8. An inert gas welder as set forth in claim 4 wherein said link meansincludes a locking means for locking said handle means in said thirdposition.

9. An inert gas welder as set forth in claim 4 including a pivotalmember disposed on said body portion, said handle means including a handreceiving portion, socket means on said handle means for engaging saidpivotal member when said handle means is in said second position and forpermitting said handle means to rotate thereabout along said second pathto said third position, a link member pivotally connected to said handlemeans at a pivotal axis, the distance between said pivotal axis and saidpivotal member being less than the distance between said hand receivingportion and said pivotal member, said link member being pivotallyconnected to a means for transmitting force to said second clampingportion, 7

and rotation of said handle means about said pivotal member to saidthird position displacing said first pivotal axis from one side of saidpivotal member to another side of said pivotal member to lock saidsecond clamping portion in said closed position.

10. An inert gas welder as set forth in claim 4 wherein said secondcontoured clamping surface includes a first surface means for engagingsaid workpiece on one side of said path and a second surface means forengaging said workpiece on the other side of said path; and said linkmeans includes a first link operatively connecting said handle means andsaid first contoured means, a second link operatively connecting saidhandle means and said second surface means, and a locking means forlocking said handle means in said third position.

11. An inert gas welder as set forth in claim 10 wherein said springmeans includes a first spring acting between said first link and saidfirst surface means, and a second spring acting between said second linkand said second surface means.

1. An inert gas welder comprising a body portion, a welding chamber, anelectrode, a carrier means for carrying said electrode along a path, anda clamping means for clamping a tubular workpiece to be welded adjacentsaid path; said clamping means including a first clamping portion havinga first contoured clamping surface, first attachment means for securingsaid first clamping portion to said body portion, a second clampingportion having a second contoured clamping surface for cooperating withsaid first clamping surface to clamp said workpiece adjacent said path,and a second attachment means for securing said second clamping portionto said body portion and for moving said second clamping portion betweenan open position away from said first clamping portion and a closedposition adjacent said first clamping portion; and said secondattachment means including handle means movable along a handle path, andspring means interconnecting said handle means and said second clampingportion for permitting movement of said handle means along said handlepath when said second clamping portion is in said closed position.
 2. Aninert gas welder as set forth in claim 1 wherein said spring meansprovides the sole means for transmitting force between said handle meansand said second clamping portion.
 3. An inert gas welder as set forth inclaim 2 wherein said second attachment means includes overcenter lockingmeans for locking said handle means in a predetermined position alongsaid handle path.
 4. An inert gas welder comprising a body portion, awelding chamber, an electrode, a carrier means for carrying saidelectrode along a path, and a clamping means for clamping a tubularworkpiece to be welded adjacent said path; said clamping means includinga first clamping portion having a first contoured clamping surface,first attachment means for securing said first clamping portion to saidbody portion, a second clamping portion having a second contouredclamping surface for cooperating with said first clamping surface toclamp said workpiece adjacent said path, and a second attachment meansfor securing said second clamping portion to said body portion and formoving said second clamping portion between an open position away fromsaid first clamping portion and a closed position adjacent said firstclamping portion; said second attachment means including handle meansmovable along a first path between a first position and a secondposition for moving said second clampinG portion between said openposition and said closed position, said handle means being furthermovable along a second path between said second position and a thirdposition, link means for transmitting a force applied to said handlemeans to said second clamping portion and for multiplying said forceapplied to said handle means solely when said second clamping portion isin said closed position and said handle means is moved from said secondposition to said third position, and said link means including springmeans for applying said increased force to said second clamping portionwhen said second clamping portion is in said closed position.
 5. Aninert gas welder as set forth in claim 4 wherein said body portionincludes means for defining said first path of movement of said handlemeans, and said link means includes means for defining said second pathof movement of said handle means.
 6. An inert gas welder as set forth inclaim 4 wherein said first path is a substantially straight line, andsaid second path is angularly related to said first path.
 7. An inertgas welder as set forth in claim 6 wherein said angular relationship issubstantially a right angle.
 8. An inert gas welder as set forth inclaim 4 wherein said link means includes a locking means for lockingsaid handle means in said third position.
 9. An inert gas welder as setforth in claim 4 including a pivotal member disposed on said bodyportion, said handle means including a hand receiving portion, socketmeans on said handle means for engaging said pivotal member when saidhandle means is in said second position and for permitting said handlemeans to rotate thereabout along said second path to said thirdposition, a link member pivotally connected to said handle means at apivotal axis, the distance between said pivotal axis and said pivotalmember being less than the distance between said hand receiving portionand said pivotal member, said link member being pivotally connected to ameans for transmitting force to said second clamping portion, androtation of said handle means about said pivotal member to said thirdposition displacing said first pivotal axis from one side of saidpivotal member to another side of said pivotal member to lock saidsecond clamping portion in said closed position.
 10. An inert gas welderas set forth in claim 4 wherein said second contoured clamping surfaceincludes a first surface means for engaging said workpiece on one sideof said path and a second surface means for engaging said workpiece onthe other side of said path; and said link means includes a first linkoperatively connecting said handle means and said first contoured means,a second link operatively connecting said handle means and said secondsurface means, and a locking means for locking said handle means in saidthird position.
 11. An inert gas welder as set forth in claim 10 whereinsaid spring means includes a first spring acting between said first linkand said first surface means, and a second spring acting between saidsecond link and said second surface means.